AnswerHi Michael. The flapper has 2 - tabs on each end. You will place this damper flap into the inside of the damper mount where the holes are to align the flap. Then you will need to remove the Microwave cover and rotate and re bolt the fan motor assy. so while in use, it will blow out -up towards the ceiling or the position you choose. As you know the mount slides into and bolts down to the top of the microwave cabinet. All of this will be illustrated in the installation guide. Thank You.